A Phenomenological Model for ‘Barrel’ Swirl in Reciprocating Engines

Abstract

Recent studies have shown that a ‘barrel’ swirl type of flow in spark ignition engines may be exploited to provide improved fuel economy and reduced emissions. A simple analytical phenomenological model of ‘barrel’ swirl has been developed for a disc-type combustion chamber that describes the vortex behaviour during compression. The model shows that the vortex can spin up during early compression but then rapidly decays as top dead centre is approached due to the high fluid shear stresses that develop. This mechanism of swirl arrestment is shown to dominate that due to wall friction. The model confirms experimental findings that show rapid swirl decay in certain four-valve engines.